Railway signaling



I. S. HULLIDAY.

RAILWAY SIGNALING. APPLICATION FILED DEC. 15. 1917.

1,324, 152, Patented Dec. 9,19I9.

SHEETS-SHEET 1.

N 4 A 7701mm.

J. S. HOLLIDAY.

RAILWAY SIGNALING.

APPLICATION FILED DEC-15,1917.

L3QJ5QQ Patented Dec. 9,1919.

2 SHEETS-SHEET 2.

UNITED STATES PATENT m JOHN S. HOLLIDAY, OF WILKINSBURG, PENNSYLVANIA,ASSIGNOR TO THE UNION SWITCH & SIGNAL COMPANY, OFSWISSVALE,PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

RAILWAY SIGNALING.

Specification of Letters Patent.

Patented Dec. 9, 11919.

Application filed December 15, 1917. Serial No. 207,252.

To all whom it may concern;

Be it known that I, JOHN S. HoLLIDAY, a

citizen of the United States, residing at Wilkinsburg, in the county ofAllegheny and State of Pennsylvania, have invented certain new anduseful Improvements in Railway Signaling, of which the following is aspecification. v

My invention relates to railway signal ing, and particularly 'tosignaling of the type embodying alternating current track circuits andalternating current track relays. More specifically, my inventionrelatesto systems of this character wherein the relay comprises two windingsone of which receives energy from the track circuit and the otherdirectly from thesource independently of the track circuit.

One object of my invention is the provision, in systems of thischaracter, of means for improving the phase relation between thecurrents in the two relay windings, and for at the same time reducing tothe lowest possible degree the amount of current which must be suppliedto the track winding of the relay through the track rails.

I will describe one form of signaling system embodying my invention, andwill then point out the novel features thereof in claims. I

' In the accompanying drawings, Figure 1 is a diagrammatic view showingone form of signaling system embodying my invention. Fig. 2 is a vectordiagram showing the conditions which would obtain in the system shown inFig. 1 if the condenser C usual, the track rails of the section, asource of alternating signaling current for supplying energy to therails adjacent one end of the section and a track relay having a windingreceiving energy from the ralls ad] acent the other end of the section.The source of signaling current, as here shown, is a generator G ofalternating current which is connected with transmission mains Pextending along the railway. Current from this source is supplied to thetrack railsadjacent one end of the section through the medium of atransformer A, whose primary is connected with said transmission mains Pand whose secondary is connected with the track rails, a reactance 3being inserted bet-Ween one rail and the transformer secondary as shown.

The relay, which is designated R, comprises a vane 4 ofelectro-conduct-ive nonmagnetizable material, such as aluminum, fixed toa shaft 5 which is j ournaled so that the vane may move in air gaps 6and 7 a in two magnetizable cores 6 and 7. Core 7 is provided with awinding 9 which is connected with the track rails T, and so I will termthis winding the track winding of the relay. Core 6 is provided with awinding 8, 8- which is connected with a secondary winding 14 of atransformer A, the primary of which is connected with the transmissionmains P. Consequently, this winding 8, 8, which I will term the linewinding of the relay, receives energy from the source G independently ofthe track rails or through the medium of means not including the trackrails. The cores 6 and 7 are so located and disposed that the fluxes inthe core 6 pass through the vane 4 substantially on opposite sides ofthe flux in core 7; that is, the air gap 7* is substantially between thetwo gaps 6*, 6 The principle of operation of a relay of this type iswell understood by those versed in the art, hence for the purposes ofthis specification it is suflicient to say that when the windings 8 and9 are supplied with alternating currents of the same frequency and ofthe proper relative phases a torque is exerted on the vane tendingtoswin it in counter-clockwise direction to drawing. When winding 9 isdenergized, however, the torque disappears and the vane swingsdownwardly in clockwise direction due to the force of gravity. The shaft5 on which the vane is mounted controls a contact 12 in such manner thatthis contact is closed when both windings of the relay areproperlyenergized, but is opened when the vane swings downwardly due todenergizathe position in which it is shown in the tion of the trackwinding 9. It is understood that a car or train in track section CDshuntsall or nearly all of the current from winding 9 so that thiswinding then becomes denergized. I

The core 7 is provided with a secondary winding 10 to which a condenser11 is connected. The function of this condenser will be explainedhereinafter.

The track section C-D is provided with a signal S for governing traflictherethrough, which signal is controlled by contact 12 of relay R in theusual and well-known manner. 7

The supply of current for this signal is obtained from a secondarywinding 13 on transformer A.

When the propulsion energy for the railway is electricity and both trackrails are included in the circuit for the propulsion current, means mustbe provided for conducting such current around the insulated joints 2.plished by the usual inductive bonds, each comprising a magnetizablecore 17, and a winding thereon the terminals of which are connected withthe two track rails; each winding has a tap at its middle point which isconnected by a conductor 16 with the corresponding tap on the adjacentbond of theadjacent track section. As is well understood, these bondsconduct the propulsion current freely from section to section, butmaintain the desired difference of potential of the signaling currentacross the rails of each section.

As is well understood, a relay R of the type herein shown operates mostefiiciently when the currents in the two windings 8 and 9 difl'er by 90in phase, and will not operate at all when these currents are of thesame phase. Owing, however, to the low power factors of these windings(about 0.3 for each), it is impossible to secure much phasedisplacement, even with the use of the reactance 3. The function of thecondenser 11 is to enable a considerable phase displacement to besecured. In order to explain how the condenser accomplishes this result,I will first show the conditions which would obtain without thecondenser, and then the conditions which obtain when the condenser isemployed.

Referring now to Fig. 2, which shows the conditions without thecondenser, the line- O-E represents the voltage applied to the trackwinding 9 of the relay, and the line OI represents the position of thecurrent in this same winding. This current lags behind the appliedvoltage by a wide angle, because the power factor of the winding is verylow-about 0.3. Assuming now that the power factor of the reactance 3 is0.1, which is about as low as can be obtained, the voltage drop acrossthis reactance is at 0.1 power factor to the current OI and so As hereshown, this is accom-' may be represented by the line EX. The totalvoltage drop across the-reactance 3 and the relay winding 9 is, then,represented by line OX. It is apparent at once that the current O-l doesnot'lag much farther behind O-X than it does behind O E. Now, thevoltage applied to the line winding 8 of the relay is nearly in phasewith the line O-X, and since the power factor of this winding is alsoabout 0.3, the cnrrent in the line winding will be in about the positionindicated by line OI It is ob vious, then, that thecurrents vin the twowindings 8 and 9 are nearly in phase, so that these windings cause verylittle torque to be exerted on the vane 4.

This difficulty is avoided by the use ofthe multiple with winding 8. Thechief reason for using the transformer arrangement shown in Fig. 1 is tostep up the volta e applied to the condenser and so ena le a smallercondenser to be used than would be the case werethis condenser connecteddirectly across the winding 9. By placing the secondary 10 directly onthe relay core 7,1 avoid the cost of a separate transformer and also thelosses due to the exciting current for a separate transformer.

Referring now to Fig. 3, the line O-lE represents the voltage applied tothe track winding 9, and the line O-I the current in this winding,exactly as in Fig. 2. The

current taken by the condenser in Fig. 4 is nearly in leading quadratureto the voltage ()E, and so is represented by line O'-'C. The current inthe track circuit is the vector sum of O-I and O-C, and may be made ofsubstantially unitypower factor so that it may be represented by lineO-S, that is, in phasewith O-E. Although the current in the trackcircuit is in the position O-S it must be borne in mind that themagnetic -flux in the core 7 is substantially in phase ponent of thecurrent taken by this wind- O-X. Since the voltage applied to the linewinding 8 isjsubstantially in phase with the voltage at the secondary oftransformer A, it follows that this voltage on the line the magneticflux in core 6. The phase displacement between the fluxes in the twocores is then represented by angle I O'I hence considerable torque willbe exerted on the vane 4. The efliciency of the relay is, consequently,good.

It is a wellknown fact that the transmission of current through trackcircuits is veryuneconomical, and it 1s very desirable, therefore, toreduce the amount of current which must be applied to the track'windingof a relay to the lowest possible value. By referring to Fig. 2 it isevident that when the condenser 11 is not used, the current which mustbe transmitted through the rails is considerable, the value beingrepresented by the line O'I but by referring to Fig. 3 it will be seenthat when the condenser is used the current which must be transmittedthrough the track rails is OS, which may be made less than one-half ofthe current 0-1 Theuse of the condenser, therefore, materially reducesthe volt-amperes which must be transmitted through the track rails.

So far as the track winding 9 alone ofthe relay is concerned, what thecondenser ac tually does is to supply the wattless coming. That is, thecondenser is of such size that the circuit of thesecondary 10 isresonant to current of the signaling frequency.

When the relay is used on an electric rail-- way employingv bonds in thetrackway as shown in Fig. 1, the condenser 11 may be ing my invention,it is understood that vamade larger than is necessary to supply thewattless component of the-current for track winding 9, and the extracurrent taken by the condenser may be made to neutralize the wattlesscomponent of the current ,for the.

bond at the relay end of the track section. Although I have shown anddescribed only one form of signaling system embodyrious chan es andmodifications may be made thereln within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1.- A railway signaling system comprising, in combination with the railsof a track section, a source of alternatin signaling current connectedwith said rails, a relay having two magnetizable cores, a'winding on onecore receiving energy from said track ralls, "a wlndlng on the othercore receiving energy from said source but not through said rails, asecondary winding on said first-mentioned core, and a condenserconnected with said secondary winding.

2. A railway signaling system comprising, in combination with the railsof a track section, a source of alternating signaling current connectedwith said rails, a relay having a trackwinding which receives energyfrom said track rails and a line winding which receives energy from saidsource but not through said rails, and means as sociated with the saidtrack winding for increasing the power-factor of the current which flowstherein.

3. A railway signaling system comprising, in combination with the railsof a track section, a source of alternating signaling current connectedwith'said rails, a re lay having a track winding which receives energyfrom said track rails and a line.

winding which receives energy from said source but not through saidralls, and a coning, in combination with the trails of a track section,a source of alternating signaling current connected with said rails, arelay having a trackwinding which receives en ergy from said track railsand a line winding which receives energy from said source but notthrough said rails, and means associated with said track winding whichtakes a wattless current leading the voltage applied to said winding.

5. A railway signaling system comprising, in combination with thetrackrails of a track section, asource of alternating signaling current, atransformer whose primary is connected with said source and whosesecondary is connected with said' rails, a reactance included in theconnection between one 'of the rails and the transformer secondary, arelay having a track winding receiving energy from said rails and a linewinding receiving energy from said source but not throu h said rails,and a condenser associated w1th said track winding and taking a wattlesscurrent leading the voltage applied to said track winding.

6. A railway signaling system comprising, in combination with the trackrails of a track section, a source of alternating signaling current, atransformer whose primary is connected with said source and whosesecondary is connected with said rails, a reactance included in theconnection between one of the rails and the transformer secondary, arelay having a track winding be substantially in phase with the voltageacross said track winding.

7. A railway signaling system comprising, incombination with the trackrails of a track section, a source of alternating signaling current, atransformer whose primary. is connected with saidsource and whosesecondary is connected with said rails, a reactance included in theconnection between one of the rails and the transformer secondary forcausing the current in the rails to lag behind the voltage across saidsecondary, a relay having a track winding receiving energy from saidrails and a line winding receiving energy from said source but notthrough said rails, the power factors of said windings being low, and acondenser associated with said track winding for causing the current inthe track rails to be substantially in phase with the voltage acrosssaid rails, whereby the fluxes pro- 1 sec;

duced by the currents in said two relay windings are displaced by aconsiderable angle.

8. A railway signaling system comprising, in combination with therailsof a track section, a source of alternating signaling currentconnected with said rails, a relay having a track Winding which receivesen ergy from said track rails and a line winding which receives energyfrom said source but not through said rails, and means associated withone of said windings which takes a wattless current leading the voltageapplied to such winding.

In testimony whereof I afiix my signature in presence of two witnesses.

JOHN S. HOLLIDAY.

Witnesses A. HERMAN WEGNER, FAY GLASGOW.

